KR20050007441A - Ceramic honeycomb structural body and method of manufacturing the structural body - Google Patents

Abstract

The ceramic honeycomb structure according to the present invention comprises a cell composite composed of a plurality of cells serving as a flow path of a fluid partitioned by a plurality of partition walls having a porous structure, and a porous material surrounding the outermost circumferential cell positioned at the outermost circumference of the cell composite. A ceramic honeycomb structure having an outer wall having a structure, wherein a portion of the partition wall positioned at at least one cell opening end of the cell composite is higher than that of the at least one cell opening end (regular partition wall). It is characterized by comprising a reinforcement partition wall part having a variation in porosity per unit volume within ± 2%, and having uniform and excellent corrosion resistance with respect to the entire reinforcement partition wall part.

Description

CERAMIC HONEYCOMB STRUCTURAL BODY AND METHOD OF MANUFACTURING THE STRUCTURAL BODY

Ceramic honeycomb structures widely used in catalyst carriers for purification of exhaust gas require higher purification performance in order to cope with the regulation of emission gas, which is reinforced year by year, while reducing pressure loss due to low fuel consumption, high output, and the like. Reduction is also required.

In such a situation, the thickness of the partition wall of the honeycomb structure is made thinner, the opening ratio at the cell opening end surface of the honeycomb structure is increased, pressure loss is reduced, and the heat capacity of the partition wall is reduced, so that the catalyst is started after the engine is started. There is a growing movement to activate early to improve purification performance.

On the other hand, with the progress of the thinning of the honeycomb structure, various foreign matters mixed in the exhaust gas collide with the partition wall existing at the cell opening end of the honeycomb structure, and the corrosion phenomenon of the partition wall becomes a new problem. have.

Above all, a honeycomb structure is proposed in which a partition wall reinforcing part (reinforced partition wall part) having a higher strength than other partition wall parts is provided in the partition wall already existing at the cell opening end (for example, Japanese patent). Various methods are also examined about the method of installing a partition wall reinforcement part.

Conventionally, as a method of providing a partition wall reinforcing portion, a substrate having a honeycomb structure containing a cordierite raw material as a main component is fired, and then the cordierite raw material is dispersed in the dispersion medium on the partition wall existing at the cell opening end of the substrate. The method of drying and baking after sticking the made slurry is known (for example, refer patent document 1).

However, this method requires a long time firing process in two stages: the firing of the base material and the firing for installing the partition wall reinforcement part, and leave a big problem in production efficiency, product cost, and the like.

On the other hand, in the step before baking a base material of a honeycomb structure, the slurry which disperse | distributed the partition wall reinforcement material to the dispersion medium was adhered to the partition wall which exists in the cell opening edge part, and it bakes the base material by one baking by drying and baking. And a method of forming a partition wall reinforcement part are suggested (for example, refer patent document 1).

However, with regard to this method, the present situation is that nothing has been specifically studied regarding the difference in material composition between the base material before firing and the base material after firing. In particular, an organic binder or the like is usually added to the base material before firing for the purpose of improving the strength of the partition wall, but no consideration has been given to the fact that most of the organic binders are water-soluble compounds such as methylcellulose. .

For this reason, performing the partition wall reinforcement formation process conventionally performed after baking using the slurry which disperse | distributed the partition wall reinforcement material in water as it is before baking is the partition wall of the honeycomb structure etc. which are obtained by eluting an organic binder in a slurry. It is a current situation that a deformation occurs and cannot be tolerated in actual use due to a decrease in isostatic strength or the like.

Further, in the slurry in which the partition wall reinforcing material is dispersed in the dispersion medium, the partition wall reinforcing material is easily precipitated or agglomerated due to its physical properties, so that the dispersibility of the partition wall reinforcing material is not easily deteriorated. It was easy to cause fluctuation or disproportionation of the. For this reason, in this manufacturing method, there is a problem that a ceramic honeycomb structure having a uniform corrosion resistance cannot be obtained stably over the entire partition wall reinforcement portion, or the management burden for uniformly distributing the partition wall reinforcement material increases. There was.

On the other hand, by using the slurry which the partition wall reinforcing material was disperse | distributed to the water-insoluble dispersion medium, the problem regarding the isostatic strength fall etc. by deformation of a partition wall etc. can be solved.

However, even in this manufacturing method, it is impossible to stably obtain a ceramic honeycomb structure having uniform corrosion resistance to the entire partition wall reinforcement portion, or increase the management burden for uniformly dispersing the partition wall reinforcement material in the slurry. None of the problems can be solved.

[Patent Document 1]

Japanese Patent Laid-Open No. 2000-51710

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and an object thereof is to provide a ceramic honeycomb structure with high uniformity and excellent corrosion resistance, and to improve productivity and to reduce the cost of the product. It is possible to obtain a honeycomb structure having a desired performance without significantly deforming the partition wall while greatly improving the efficiency of the partition wall, and furthermore to provide a method for producing a ceramic honeycomb structure which can precisely form a dense and uniform reinforcement partition wall part with high accuracy. Is in.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic honeycomb structure and a method for manufacturing the same, and to a ceramic honeycomb structure and a method for manufacturing the same, which are suitable as a carrier for purifying automobile exhaust gas having a balance in purifying performance, endurance, and canning.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the site | part of the sample which was taken at the time of obtaining porosity 1 (cross-products) about the ceramic honeycomb structure of each Example and each comparative example.

FIG. 2 is a schematic diagram showing a portion of a sample taken when the porosity 2 (uniformity of a reinforced partition wall part) is obtained for the ceramic honeycomb structures of each example and each comparative example. FIG.

3 is an enlarged view showing a part of the partition wall in the ceramic honeycomb structure obtained by the manufacturing method of Example 1. FIG.

4 is an enlarged view showing a part of the partition wall in the ceramic honeycomb structure obtained by the manufacturing method of Comparative Example 2. FIG.

5 is an explanatory view schematically showing an embodiment of the ceramic honeycomb structure of the present invention, Figure 5a is a perspective view, Figure 5b is a plan view, Figure 5c is a side view respectively.

6 is a partially enlarged view schematically showing another embodiment of the ceramic honeycomb structured body of the present invention.

Fig. 7 is an explanatory diagram schematically showing an example in which the ceramic honeycomb structure of the present invention is incorporated in a converter container.

8 is a diagram illustrating conditions of engine speed in a corrosion test.

9 is an explanatory diagram schematically showing a method for measuring the amount of corrosion.

As a result of earnestly examining in view of the above-mentioned problems, the present inventors have found that, as a partition wall reinforcing agent, a compound having as its main component a structure having at least one element selected from the group consisting of Si, Ti, Mg, and Al, such as silicon oil, in its structure By using it, it discovered that the above-mentioned problem could be solved and came to complete this invention.

That is, according to the present invention, a cell composite composed of a plurality of cells serving as a flow path of a fluid partitioned by a plurality of partition walls having a porous structure, and a porous material surrounding the outermost circumferential cell positioned at the outermost circumference of the cell composite. A ceramic honeycomb structure having an outer wall having a structure, wherein a part of the partition wall positioned at at least one cell opening end of the cell composite is higher than a portion other than the at least one cell opening end (regular partition wall part). In addition, there is provided a ceramic honeycomb structure, comprising a reinforcing partition wall having a variation in porosity per unit volume within ± 2%.

In this invention, it is preferable that the value of the porosity (%) of a reinforced partition wall part is 3% or less smaller than the value of the porosity (%) of a normal partition wall part. In this invention, it is preferable that the porosity of a reinforced partition wall part is 30% or less.

In this invention, it is preferable that the minimum partition wall thickness of a partition wall is 0.030-0.076 mm, and it is preferable that the length from the end surface of the cell opening edge part of a reinforcement partition wall part to the front-end | tip is not the same as the whole reinforcement partition wall part.

In this invention, it is preferable that the partition wall thickness of a reinforcement partition wall part is thicker than the partition wall thickness of a regular partition wall part.

In the present invention, when the outermost circumferential cell is a starting cell or any cell within the third to twenty-second range located inward from the starting cell, the starting cell and the cell located inside the ending cell are the starting cells, and The thicknesses (Tr ₁ , Tr _3-20 ) of the partition walls constituting each of the end cells and the thicknesses (Tc) of the partition walls constituting the base cell are 1.10≤ (Tr ₁ , Tr _3-20 ) /Tc≤3.00 It is desirable to satisfy the relationship.

In the present invention, it is preferably composed of at least one ceramic selected from the group consisting of cordierite, alumina, mullite, silicon nitride, aluminum titanate, zirconia and silicon carbide.

In the present invention, the cross-sectional shape perpendicular to the flow path is preferably a circle, an ellipse, a manor, a trapezoid, a triangle, a square, a hexagon, or a bilateral asymmetric shape, and the cross-sectional shape perpendicular to the flow path of the cell is a triangle, a square, or a hexagon. It is preferable.

The ceramic honeycomb structure according to the present invention is preferably used as a carrier for purification catalysts for automobile exhaust gases, and is preferably embedded in a catalytic converter by carrying a catalyst component on a partition wall and holding it on the outer circumferential surface of the outer wall.

Further, according to the present invention, a base material which is a dry body having a honeycomb structure having a plurality of partition walls using a clay material composed mainly of a ceramic material is obtained, and is located at at least one cell opening end of the base material among the partition walls. A method of manufacturing a ceramic honeycomb structure which is fired after attaching a partition wall reinforcement to a portion, wherein the partition wall reinforcement includes a compound having at least one element selected from the group consisting of Si, Ti, Mg and Al in the structure as a main component. There is provided a method for producing a ceramic honeycomb structure, characterized in that it is used.

In this invention, it is preferable that it is a compound which produces | generates an inorganic oxide by burning the main component of a partition wall strengthening agent, and it is more preferable that it is a compound which has a siloxane bond. Specifically, a partition wall reinforcing agent based on silicone oil, silicone varnish, alkoxy oligomer or a mixture thereof is preferable.

The partition wall reinforcing agent preferably has an absolute viscosity of 1 to 100 000 mPa · s, and preferably contains a compound having this absolute viscosity as a main component.

In addition, although various materials can be used as a ceramic material in this invention, it is preferable to select the kind of a partition wall reinforcement according to the kind of raw material, For example, when using a cordierite raw material, a silicon oil etc. Compounds having Si in the structure are preferred.

In addition, in the present invention, in the case of containing soil-soluble organic binder in addition to the ceramic material as the main component in the clay, the effect is particularly great, and specific water-soluble organic binders include, for example, hydroxypropylmethyl cellulose, methyl cellulose, hydroxyethyl cellulose, The thing which consists of 1 or more types of water-soluble compounds chosen from the group which consists of carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl acetal is mentioned.

Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples. The ceramic honeycomb structure according to the present invention comprises a cell composite composed of a plurality of cells serving as a flow path of a fluid partitioned by a plurality of partition walls having a porous structure, and a porous body surrounded by an outermost cell positioned at the outermost periphery of the cell composite. A ceramic honeycomb structure having an outer wall having a structure, wherein a part of the partition wall positioned at at least one cell opening end of the cell composite is a portion other than at least one cell opening end (hereinafter abbreviated as "regular partition wall part"). It is characterized by comprising a reinforcement partition wall having a higher strength than that and having a porosity variation (hereinafter abbreviated as "porosity maximum crossing") per unit volume within ± 2%. This will be described in detail below.

FIG. 5 is an explanatory view schematically showing an embodiment of the ceramic honeycomb structure of the present invention, FIG. 5A is a perspective view, FIG. 5B is a plan view, and FIG. 5C is a side view, respectively. 6 is a partially enlarged view schematically showing another embodiment of the ceramic honeycomb structure according to the present invention. The ceramic honeycomb structure 1 is composed of a cell composite composed of a plurality of cells 3 serving as a flow path of a fluid partitioned by a plurality of partition walls (cell partition walls 2) having a porous structure and at the outermost circumference of the cell composite. The outer wall 4 which has a porous structure surrounding and holding the outermost periphery cell 8 located is provided. In addition, in FIG. 6, the code | symbol 2a shows an outer periphery cell partition wall, the code | symbol 2b shows a basic cell partition wall, and the code | symbol 9 shows the 2nd cell from outermost periphery.

In the ceramic honeycomb structure 1 of the embodiment shown in FIG. 5, a portion of the partition wall (cell partition wall 2) positioned at at least one cell opening end 5 of the cell composite has a higher strength than the regular partition wall portion. I construct a reinforcement partition wall part. Therefore, the ceramic honeycomb structure 1 of this embodiment has excellent corrosion resistance.

In addition, the maximum porosity crossing of the reinforcement partition walls is within ± 2%, that is, the homogeneity is very high. Therefore, the ceramic honeycomb structure 1 of this embodiment has very little variation in the ease of occurrence of corrosion in each part of the reinforced partition wall portion, and can avoid local corrosion phenomenon, thereby providing excellent corrosion resistance to the entire reinforced partition wall portion. Is given.

In the ceramic honeycomb structure of the present embodiment, from the viewpoint of providing more excellent corrosion resistance, it is preferable that the maximum porosity crossing between the five portions of the reinforcing partition wall portion is within ± 1.5%, and within ± 1%. More preferably. In addition, the "porosity maximum intersection of a reinforced partition wall part" as used in this invention means the fluctuation | variation of the porosity per unit volume between five arbitrary parts in a reinforced partition wall part specifically ,.

In this embodiment, the porosity (%) value of the reinforcement partition wall part is preferably 3% or more smaller than the porosity (%) value of the regular partition wall part, more preferably 5% or more small, particularly preferably 8% or less small. . If the value of the porosity (%) of the reinforcing partition wall part is less than 3% less than the value of the porosity (%) of the normal partition wall part, it is not preferable because sufficient corrosion resistance is hardly exerted. The upper limit of the small degree seen from the porosity (%) value of the normal partition wall portion of the reinforcement partition wall portion is not particularly limited, but may be about 12% or less.

In addition, in this embodiment, in consideration of providing both characteristics of thermal shock resistance and corrosion resistance, the porosity of the reinforcement partition wall portion is preferably 30% or less, more preferably 13-25%, and is 15-23%. It is especially preferable, and it is most preferable that it is 18 to 21%.

In the present embodiment, the minimum partition wall thickness of the partition wall is preferably 0.030 to 0.076 mm, more preferably 0.030 to 0.065 mm. By defining the minimum partition wall thickness within such a numerical range, it is possible to improve the purifying performance in warm air by reducing the weight loss and reducing the heat capacity while reducing the pressure loss.

The reinforcement partition wall portion is preferably provided in a part or whole within a range of 30 mm in the axial direction from at least one end face of the cell opening end in terms of achieving compatibility between corrosion resistance and low heat capacity. It is more preferable that it is provided in part or all of the range within 10 mm. Further, in the ceramic honeycomb structure of the present embodiment, the reinforcement partition wall portion may be provided with the same length in the axial direction from the end face of the cell opening end portion, but the length from the end face of the cell opening end portion of the reinforcement partition wall portion to its tip is What is not the same as the whole reinforcement partition wall part is preferable at the point which aims at the compatibility with corrosion resistance and low heat capacity, and the point which aims at the relaxation of the stress concentration of the boundary part to which a porosity changes.

In this embodiment, it is preferable that the partition wall thickness of the reinforcement partition wall part is thicker than the partition wall thickness of the regular partition wall part. Specifically, the partition wall thickness of the reinforcing partition wall portion is preferably 1.20 to 4.00 times the thickness of the partition wall thickness of the regular partition wall portion. In addition, it is preferable for the partition wall thickness of the reinforcement partition wall portion to be continuously or stepwise thinned in the axial direction from at least one end face of the cell opening end portion to the partition wall thickness of the regular partition wall portion to prevent stress concentration. Moreover, these various reinforced partition wall parts can be comprised individually by 1 type or in combination of 2 or more types.

In the present invention, as in the embodiment shown in Fig. 6, it is also preferable to thicken the cell partition wall 2a on the outer peripheral part side in terms of improving the corrosion resistance. In addition, by increasing the cell partition wall 2a on the outer circumferential side, the isostatic strength can be improved, and the gripping force at the time of canning can be enhanced, so the canning performance is also improved. Here isostatic strength is the intensity | strength expressed by the pressurized pressure value at the time of destruction by the test based on the automobile standard JASO standard M505-87. In FIG. 6, the outermost cell 8 is closest to the outer wall 4, and the second cell 9 is continuous inward from the outermost cell 8. The partition wall thickness of the outermost cell is denoted by Tr ₁ , and the partition wall thickness of the second cell 9 is denoted by Tr ₂ . Although not shown, similarly, the thickness of the partition wall of any cell in the _{5th to 15th ranges} is represented by Tr _{5 to 15} . The cell partition wall 2 is roughly divided into an outer circumferential cell partition wall 2a and a basic cell partition wall 2b.

In the present embodiment, when the outermost circumferential cell is a starting cell or any cell in the 3rd to 20th ranges positioned inside the starting cell, the starting cell and the cell located inside the ending cell are the starting cells. And the thicknesses (Tr ₁ , Tr _3-20 ) of the partition walls constituting each of the end cells and the thicknesses (Tc) of the partition walls constituting the basic cells are 1.10 ≦ (Tr ₁ , Tr _3-20 ) /Tc≦3.00 It is desirable to satisfy the relationship of. If this value [(Tr ₁ , Tr _{3 to 20} ) / Tc] is less than 1.10, it does not contribute to improvement of corrosion resistance and does not contribute to improvement of isostatic strength, and therefore does not contribute to improvement of canning performance. Moreover, when it exceeds 3.00, heat capacity and pressure loss will increase. In addition, even if the partition wall thicknesses (Tr ₁ , Tr ₂ ) of the first and second cells are thickened at a specific ratio, they do not contribute to the improvement of the corrosion resistance or the isostatic strength, and the partition walls of the cells after the 21st, especially after the 31st, and the like. If the thickness is made thick at a specific ratio, the pressure loss increases and the mass of the ceramic honeycomb structure increases by more than a predetermined value, thereby increasing the heat capacity, which is undesirable.

In the present embodiment, each of the cell partition wall thicknesses Tr ₁ and Tr _{3 to 20} is set to 1.10 ≦ (Tr ₁ , Tr _{3 to 20} ) /Tc≦2.50, between the basic cell partition wall thicknesses Tc. Furthermore, it is preferable in practical use to consider the heat capacity or the pressure loss in a more limited condition so as to have a relationship of 1.20 ≦ (Tr ₁ , Tr _{3 to 20} ) /Tc≦1.60.

The ceramic honeycomb structure of this embodiment is made of, for example, at least one ceramic selected from the group consisting of cordierite, alumina, mullite, silicon nitride, aluminum titanate, zirconia and silicon carbide.

Moreover, as a cross-sectional shape perpendicular | vertical to the flow path of the ceramic honeycomb structure of a present Example, the shape of a circle, an ellipse, an ellipse, a trapezoid, a triangle, a square, a hexagon, or a bilateral asymmetry is mentioned, for example. Especially, it is preferable that it is any of a circle, an ellipse, or a manor.

As a cross-sectional shape perpendicular | vertical to the flow path of the ceramic honeycomb structure cell of a present Example, a polygonal shape more than triangular, for example, a square, a rectangle, a hexagon, etc. are mentioned. Especially, it is preferable that it is any of a triangle, a square, or a hexagon.

The use of the ceramic honeycomb structure according to the present embodiment is not particularly limited, and can be used for various applications such as various filters and catalyst carriers, but it is particularly preferable to use the carrier for purification catalysts for automobile exhaust gas. In addition, it is preferable that the ceramic honeycomb structure of this embodiment is incorporated in the catalytic converter container 11, as shown in FIG. Here, the ceramic honeycomb structure 13 is embedded in the catalytic converter container 11 with its outer circumferential surface held by a ring 12. Although there is no restriction | limiting in particular in the material which comprises the ring 12, What is normally made of a metal mesh is used. Moreover, it is preferable to interpose the holding material 14, such as a mat and a cross, between the catalytic converter container 11 and the outer peripheral surface of the ceramic honeycomb structure 13.

Next, an embodiment of the manufacturing method of the ceramic honeycomb structure of the present invention will be described. The method for producing a ceramic honeycomb structure of the present invention obtains a substrate which is an unbaked dry body having a honeycomb structure having a plurality of partition walls by using clay containing ceramic material as a main component, and at least one cell opening of the substrate in the partition walls. A method for producing a ceramic honeycomb structure which is fired after attaching a partition wall reinforcement to a portion located at an end, wherein the partition wall reinforcement is formed of at least one element selected from the group consisting of Si, Ti, Mg, and Al. It is characterized by using what has a compound as a main component.

In this embodiment, since the firing of the base material (regular partition wall part) and the formation of the reinforcement partition wall part can be performed simultaneously by one firing, it is possible to greatly improve the productivity and the cost reduction of the product. In addition, since a hydrophobic compound is used as the partition wall reinforcing agent, a ceramic honeycomb structure having a desired performance can be obtained when the water-soluble organic binder does not dissolve and swell when attached to the partition wall and there is no deformation of the partition wall such as cell twisting. have.

In addition, in this embodiment, since the compound which has an element which contributes to partition wall reinforcement in a structure is used as a partition wall reinforcing agent, the element which contributes to partition wall reinforcement will always be arrange | positioned uniformly in the physicochemical shaping | molding. For this reason, a uniform reinforcement partition wall part can be formed especially without taking measures, such as dispersion | distribution, and it can hardly prevent local corrosion generation. Therefore, even when the average porosity of the whole reinforcement partition wall part is made the same, the reinforcement partition wall part which is more excellent in corrosion resistance than a conventional ceramic honeycomb structure can be formed. In addition, by using the partition wall reinforcing agent, there is no variation in corrosion resistance between products, and a ceramic honeycomb structure excellent in corrosion resistance can be stably obtained by a simple process. Hereinafter, it demonstrates concretely for every process.

In the present embodiment, first, a molded article having a honeycomb structure having a plurality of partition walls is produced by using clay having a ceramic material as a main component.

There is no restriction | limiting in particular regarding a ceramic material in this Example, For example, silicon carbide, boron carbide, titanium carbide, zirconium carbide, silicon nitride, boron nitride, aluminum nitride, alumina, zirconia, mullite, cordierite raw material, titanic acid One or more types selected from the group consisting of aluminum and sialon can be used. In addition, the relationship of the kind of partition wall reinforcement is mentioned later.

In the present embodiment, other additives may be contained in the clay if necessary, and for example, a water-soluble organic binder, a crystal growth aid, a dispersant, or a pore-forming agent may be included. Moreover, as a water-soluble organic binder, hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl acetal, etc. are mentioned, for example. Examples of the crystal growth aid include magnesia, silica, yttrium oxide and iron oxide. Examples of the dispersant include ethylene glycol, dextrin, fatty acid soap, polyalcohol, and the like. In addition, examples of the pore-forming agent include graphite, wheat flour, starch, phenol resin or polyethylene terephthalate. Moreover, these additives may be contained 1 type or in mixture of 2 or more types according to the objective.

In addition, in the present embodiment, since the hydrophobic compound is used as the partition wall reinforcing agent as described above, the water-soluble organic binder does not dissolve and swell when adhered to the partition wall, and partition wall deformation such as cell twist occurs. There is no work. Therefore, it can apply especially preferably as a manufacturing method which makes the said water-soluble organic binder into a clay.

In addition, the clay may be produced by a conventional method. For example, a predetermined amount of water or the like is mixed with a raw material to which an additive such as a water-soluble organic binder is added to a ceramic material, and other additives are added if necessary, followed by kneader or pressurization. It can be obtained by kneading and kneading with a kneader or a vacuum grinding machine.

Although there is no restriction | limiting in particular also about the method (molding method) which obtains the molded object of a honeycomb structure in this Example, Extrusion molding is preferable at the point which is excellent in mass productivity, for example, a ram type extrusion machine or a twin screw continuous extrusion machine. It is preferable to perform extrusion molding using extrusion apparatuses, such as these.

In addition, in this embodiment, there is no restriction | limiting in particular also about the partition wall thickness (the partition wall thickness of a regular partition wall part) of a base material, For example, even if a base material with a partition wall thickness of 0.05 mm or less, a desired honeycomb structure can be made without causing deformation to a partition wall. The molded object which has is obtained. Then, the obtained molded object is dried and the base material which is a dried body which has a honeycomb structure is obtained. What is necessary is just to employ | adopt an appropriate drying method for drying a molded object, and to dry at the temperature which is not baked substantially. As a drying method, ventilation drying, hot air drying, microwave drying, etc. are mentioned, for example. In addition, in this invention, when it means a "drying body", it means an unbaked dry body which is not substantially baked.

As a present Example, a partition wall reinforcing agent is affixed to the some partition wall currently existing in the cell opening edge part of the base material (drying body) obtained by the pre-firing step.

In this embodiment, when the cell wall is attached to the substrate as the partition wall reinforcing agent, the partition wall existing at the end portion is reduced by lowering the melting point of the substrate constituent material or infiltrating into the partition wall pores to reduce the volume of the pores. The compound which has a densified element, more specifically, the compound which has at least 1 sort (s) of element selected from the group which consists of Si, Ti, Mg, and Al in a structure as a main component is used.

In this embodiment, as the compound which is the main component of such a partition wall reinforcing agent, a compound which produces an inorganic oxide by burning is preferable.

Moreover, as a compound which has Ti or Al in a structure, the titanate alkoxy oligomer used as a coupling agent or aluminate alkoxy oligomers, such as acetoalkoxy aluminum diisopropylate, etc. are preferable, for example.

Moreover, as a compound which has Si in a structure, the compound etc. which have a siloxane bond are preferable, For example, silicone oil, a silicone varnish, a silicate alkoxy oligomer, a mixture thereof, etc. are preferable.

As the silicone oil, for example, dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, amino modified silicone oil, epoxy modified silicone oil, carboxy modified silicone oil, carbinol modified silicone oil, methacryl modified silicone oil, mercury Capped modified silicone oil, phenol modified silicone oil, single-ended reactive silicone oil, heterofunctional modified silicone oil, polyether modified silicone oil, methyl styrene modified silicone oil, alkyl modified silicone oil or higher fatty acid ester modified silicone oil have.

In the present embodiment, the above-described various compounds may be mixed alone or in combination of two or more thereof to prepare the partition wall reinforcing agent. In particular, it is preferable to mix the two or more types to prepare the partition wall reinforcing agent. When the partition wall reinforcing agent is prepared by mixing two or more of the compounds, the compound having various viscosities can be selected and mixed, so that the viscosity of the partition wall reinforcing agent can be arbitrarily adjusted, and the uniform adhesion of the partition wall reinforcing agent is easy. Become. Further, by arbitrarily selecting and mixing the above compounds, the degree of reinforcement of the partition wall can be arbitrarily controlled while ensuring the desired thermal shock resistance, and the desired corrosion resistance can be imparted according to the partition wall thickness or the like.

Specifically, for example, it is preferable to use a partition wall reinforcing agent in which silicate alkoxy oligomer or methylhydrogen silicone oil is mixed with dimethyl silicone oil.

In addition, the partition wall reinforcing agent is a silicate alkoxy oligomer (SAO) or methylhydrogen silicone oil (MHSO) and dimethyl silicone oil (DMSO) of the mixing ratio (SAO or MHSO / DMSO) of 10/90 to 75/25 ( Mass ratio), more preferably 15/85 to 50/50 (mass ratio), still more preferably 20/80 to 50/50 (mass ratio), and 25/75 to 50/50 (mass ratio) Is particularly preferred. If the mixing ratio is within this range, it is possible to obtain a ceramic honeycomb structure having excellent corrosion resistance while securing desired thermal shock resistance.

In addition, the partition wall reinforcing agent in the present embodiment is a compound such as silicone oil, aromatic hydrocarbons such as toluene or xylene, aliphatic hydrocarbons such as petroleum ether or kerosene, petroleum hydrocarbons such as kerosene or diesel, isopropyl alcohol. And diluent containing 1 type (s) or 2 or more types, such as alcohols, such as lauryl alcohol or butanol, or volatile silicone oil, may be sufficient. The addition of such diluent can arbitrarily control the degree of reinforcement of the partition wall, and furthermore, the viscosity of the partition wall reinforcement can be arbitrarily adjusted, so that the uniform adhesion of the partition wall reinforcement is facilitated.

The partition wall reinforcing agent in the present embodiment preferably has an absolute viscosity of 100 to 100 mPa · s, more preferably 10 to 100 mPa · s.

In general, low-viscosity compounds have a low degree of polymerization and tend to be volatilized. When the viscosity is less than 1 mPa · s, Si, which is present in the partition wall reinforcement at the same time as CO ₂ and H ₂ O, is adhered to the partition walls and calcined. Since the active ingredient of volatilizes, it becomes difficult to form a strong reinforced partition wall part. On the other hand, when the viscosity exceeds 100 mPa · s, it becomes difficult to attach the partition wall reinforcing agent to the partition wall with a uniform thickness.

In addition, it is preferable that the partition wall reinforcing agent in a present Example selects the thing suitable for every kind of ceramic raw material, For example, the compound which has Si, such as a silicon oil, in the structure is selected for the clay which has a cordierite raw material as a main component. It is desirable to.

In the present embodiment, when the partition wall reinforcement is attached to the partition wall, immersing the substrate in the partition wall reinforcement to the desired height from the end face of the cell opening end can easily attach the partition wall reinforcement uniformly to all the partition walls. Moreover, it is preferable at the point which it is easy to arbitrarily control the area | region which installs a reinforcement partition wall part. However, in order to uniformly adhere the partition wall reinforcing agent, it is preferable to remove the partition wall reinforcing agent that is excessively adhered after immersion by compressed air or the like. In addition, even when spray coating, homogeneous application of the partition wall reinforcing agent is possible, but it is difficult to arbitrarily control an area where the reinforcing partition wall is provided.

In the present embodiment described below, the baking (forming) of the regular partition wall portion and the baking (forming) of the reinforcement partition wall portion are performed simultaneously by performing at least one firing on the base material of the honeycomb structure to which the partition wall reinforcing agent is attached.

In the present Example, in baking of a base material, it is preferable to dry a base material and a partition wall reinforcing agent beforehand, As a drying method, air drying, hot air drying, microwave drying, etc. are mentioned.

In addition, it is preferable to select conditions suitably according to the kind of base material and a partition wall reinforcement about the conditions at the time of baking, for example, a base material mainly uses a cordierite-ized material, and a partition wall reinforcement is made of silicone oil etc. What is necessary is just to bake at 1300-1500 degreeC when the compound which has Si in a structure is a main component.

As mentioned above, although the manufacturing method of this Example was demonstrated for every process, the manufacturing method of this Example can stably manufacture the ceramic honeycomb structure excellent in corrosion resistance by one baking process, without causing deformation etc. to a partition wall, and is high productivity. And it is possible to achieve a significant cost reduction of the product.

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples.

Example 1

A mixture of 8 parts by mass of methyl cellulose, 0.5 parts by mass of potassium laurate soap, 2 parts by mass of polyether and 28 parts by mass of water was added to 100 parts by mass of the ceramic raw material composed of the cordierite raw material, and the honey was introduced into a continuous extrusion molding machine. The molded object which has a comb structure was obtained, and it dried and the base material (micro-baked dry body) which has a honeycomb structure was produced.

Next, a partition wall reinforcing agent composed of dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF96-100CS, absolute viscosity: about 100 mPa · s) was axially formed from the cell opening end face. Dipping to a depth of mm allowed the partition wall reinforcing agent to adhere to the partition wall present at the cell opening end of the substrate. In addition, immediately afterwards, compressed air at room temperature was blown to remove the adhered partition wall reinforcing agent.

Subsequently, the honeycomb structured substrate having the partition wall reinforcing agent attached to the partition wall existing at the cell opening end was baked at 140 ° C. for 4 hours, and the partition wall thickness was 0.064 mm, diameter 100 mm, height 100 mm, A cylindrical ceramic honeycomb structure (uncatalyzed catalyst) having an opening ratio of 85.5% having a density of 140 cells / cm ² was prepared. Moreover, the porosity of the regular partition wall part of the manufactured ceramic honeycomb structure was 27 to 28%.

(Examples 2 to 4)

As the partition wall reinforcing agent, methylhydrogen silicone oil (manufactured by Shin-Etsuka Chemical Co., Ltd., brand name: KF99, absolute viscosity: 20 mPa.s) and dimethyl silicone oil (manufactured by Shin-Etsuka Chemical Co., Ltd., brand name: KF96L- The ceramic honeycomb structural body was formed in the same manner as in Example 1, except that 0.65 CS and absolute viscosity: 0.65 mPa · s) were mixed at a ratio (mass ratio) of 10/90, 25/75, and 50/50, respectively. Manufactured.

(Examples 5-7)

As a partition wall reinforcing agent, silicate alkoxy oligomer (manufactured by Shin-Etsuka Chemical Co., Ltd., brand name: KR-500, absolute viscosity: 20 mPa · s) and dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KF96L- The ceramic honeycomb structural body was formed in the same manner as in Example 1, except that 0.65 CS and absolute viscosity: 0.65 mPa · s) were mixed at a ratio (mass ratio) of 10/90, 25/75, and 50/50, respectively. Manufactured.

(Examples 8 to 10)

As the partition wall reinforcing agent, methylhydrogen silicone oil (manufactured by Shin-Etsuka Chemical Co., Ltd., brand name: KF99, absolute viscosity: 20 mPa.s) and dimethyl silicone oil (manufactured by Shin-Etsuka Chemical Co., Ltd., brand name: KF96L Ceramic honeycomb structured in the same manner as in Example 1 except for using a mixture of -1000 CS and absolute viscosity: 1000 mPa · s at a ratio (mass ratio) of 10/90, 25/75, and 50/50, respectively. Prepared.

(Example 11)

As a partition wall reinforcing agent, methylhydrogen silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KF99, absolute viscosity: 20 mPa · s), and kerosene (Nihon Sekiyu Mitsubishi Corporation) are 25/75 A ceramic honeycomb structural body was produced in the same manner as in Example 1, except that the mixture was used in a proportion (mass ratio).

(Comparative Example 1)

A honeycomb structural body was produced in the same manner as in Example 1 except that the partition wall reinforcing agent was not attached to the base material of the honeycomb structural body.

(Comparative Example 2)

Using water as a dispersion medium, a silica (SiO ₂₎ a dispersing agent to 100 parts by mass of the dispersion liquid was 5% by mass dispersion powder (alkyl acetalized polyvinyl alcohol / Sekisui car manufacturing manufactured by greater Kogyo K.K., trade name: S recreational KW-3 A ceramic honeycomb structural body was produced in the same manner as in Example 1, except that the partition wall reinforcing agent containing 0.5 parts by mass of) was used.

(Comparative Example 3)

100 mass dispersion of 5 mass% silica (SiO ₂ ) powder dispersed using petroleum hydrocarbon (manufactured by Nippon Seki Oil Mitsubishi Corp., product name: kerosene / kurifsefoil F8 mixed oil, main ingredient: kerosene) as a dispersion medium. In the same manner as in Example 1, except that the partition wall reinforcing agent to which 0.5 parts by mass of a dispersant (polyoxyalene group polymer / Nihon Oil and Fats Co., Ltd., trade name: Mariarim AKM-0531) was added was added to the ceramic honeycomb. The comb structure was produced.

The porosity, corrosion resistance, isostatic strength and thermal shock resistance of the ceramic honeycomb structures obtained in the examples and the comparative examples were evaluated as follows.

1. Porosity 1 (cross between products)

Five ceramic honeycomb structures obtained by each example and each comparative example were cut out of the sample 6 for measurement in the range of 70 cm ² which is almost the entire surface of the end face with respect to the reinforced partition wall portion. The porosity of each measurement sample was measured by the method shown below, and the maximum crossover was calculated | required.

2. Porosity 2 (uniformity of reinforced partition wall)

As an evaluation of whether or not the entire reinforcement partition wall has uniform corrosion resistance, the end face of the reinforcement partition wall of one ceramic honeycomb structure obtained by each example and each comparative example as shown in FIG. The sample 7 for measurement was cut out in the range of 9 cm <^2> in 1 center part of 1 place and 4 outer peripheral parts in total, and the porosity of each measurement sample was measured by the method shown below, and the maximum crossover was calculated | required. .

3. Measurement of porosity

(1) The measurement sample was dried at 150 ° C. for 2 hours, and then placed in a container and set in the apparatus.

(2) Mercury was inject | poured in the container, the pressure corresponding to the defined pore diameter was applied, and the volume of mercury absorbed by the measurement sample was calculated | required.

(3) Pore distribution was calculated and calculated from pressure and absorbed mercury volume.

(4) The pore volume was calculated by calculating the volume of mercury absorbed by applying a pressure of 68.6 Mpa (700 kgf / cm ² ).

(5) Porosity was calculated | required by the following formula from total pore volume.

Porosity (%) = total pore volume (per g) x 100 / [total pore volume (per g) + 1 / 2.52]

4. Corrosion resistance

A four-cylinder, 1.8-liter gasoline engine exhaust port was connected to a metal can in which a ceramic honeycomb structure was held and housed. That is, the sample was placed in the immediate vicinity of the engine. Next, the engine was operated under the conditions shown in FIG. 8, and 0.1 g of abrasive grains (silicon carbide, GC320, an average particle diameter of 50 μm) was added when the rotation speed reached 6000 rpm. Furthermore, the engine operation was continued on the conditions shown in FIG. 8, 130 seconds was used as 1 cycle, and abrasive grain was thrown in once every 2 cycles, and this was repeated continuously. The total abrasive grain loading was changed to about 2 g to 16 g and tested several times. From the results, the amount of corrosion (air volume) of the ceramic honeycomb structure when the abrasive grain loading was 10 g was calculated.

As shown in FIG. 9, a rubber sheet is wound around the processing end surface of the side which measures the corrosion amount of the ceramic honeycomb structure 1, and the ceramic manufacturing bead 20 of diameter 1.5mm in it is about 3 mm. After filling it with height, it collect | recovered and measured the bead volume, the difference between the bead volume after a corrosion test and the bead volume before a test was calculated | required, and it was set as the average amount of corrosion performed 3 times. In addition, evaluation is performed about the three ceramic honeycomb structures obtained by each Example and each comparative example, and the case where corrosion generation amount exceeded 3 cc total cannot be tolerated actual use, and corrosion generation amount is 2 cc or less. (Triangle | delta) was evaluated for the case where the thing and more than 3 cc were mixed, (circle) and the case where corrosion generation amount was 2-3 cc in total, and the case where corrosion generation amount is less than 2 cc in total.

5. Isostatic strength

The pressurized pressure value at the time of breaking was measured by carrying out the test based on the automobile standard JASO standard M 505-87, and this value was made into isostatic strength (kg / cm <^2> ).

6. Thermal shock resistance

The ceramic honeycomb structure is heated to a predetermined temperature in an electric furnace and then extracted in a room temperature atmosphere at 20 ° C., and defects such as cracks due to thermal shock in the state of high temperature immediately after extraction and after cooling by cold wind (state at 20 ° C.) It was observed by eye to see if this occurred. When the observation did not confirm the occurrence of a defect, the heating temperature was further increased, the test was repeated until the temperature at which the defect occurred, the limit temperature at which the occurrence of the defect was confirmed, and the thermal shock resistance was evaluated.

(evaluation)

In the manufacturing method of the comparative example 1 which does not use a partition wall reinforcing agent, it was confirmed that the porosity of the partition wall edge part of five obtained ceramic honeycomb structures is all 27-28%, and corrosion resistance cannot endure actual use.

In addition, in the manufacturing method of Comparative Example 2 using the partition wall reinforcing agent in which silica (SiO ₂ ) powder was dispersed in water, the remarkable degree that can be clearly seen visually on the partition wall of the ceramic honeycomb structure obtained as shown in FIG. Deformation was confirmed, and the isostatic strengths of the five obtained ceramic honeycomb structures were also very small at 3 to 5 kg / cm ² and were not able to withstand actual use. In addition, between the five ceramic honeycomb structures, the maximum crossover of the average porosity at the reinforcing partition wall was 5%, and the corrosion resistance was 1.2 to 3.2 cc, which caused a great variation between the products. In addition, even in one ceramic honeycomb structure, the maximum crossing rate of porosity is 5%, and since the local corrosion phenomenon is likely to occur as compared with the ceramic honeycomb structure obtained in the examples described later, the average porosity of the entire reinforced partition wall is the same. The lower corrosion resistance was suggested.

Similarly, in the manufacturing method of Comparative Example 3 using the partition wall reinforcing agent in which silica (SiO 2) powder was dispersed in petroleum hydrocarbon, the maximum crossover of the average porosity of the entire reinforcing partition wall portion between the five ceramic honeycomb structures obtained was 8%. The corrosion resistance was also 1.1-3.5 cc, which caused more variation between products. In addition, it was suggested that even in one ceramic honeycomb structure, the maximum crossing rate of porosity is larger than 7%, and local corrosion phenomenon is more likely to occur in the reinforcement partition wall.

On the other hand, in the manufacturing method of each Example which attaches the partition wall reinforcement which consists of a compound which has Si in a structure to a partition wall, as shown in FIG. 3 (FIG. 3 shows the ceramic honeycomb structure obtained by Example 1). There is no deformation of the partition wall, and the isostatic strength is 21 kg / cm ² or more, so there is no problem in actual use. Furthermore, it was suggested that the average porosity of the entire reinforcement partition wall was 14 to 24%, 3 to 13% lower than that of the unreinforced portion, and large corrosion resistance. Moreover, it was confirmed that the maximum crossing of the average porosity of the whole reinforcement partition wall part among 5 ceramic honeycomb structures is 1%, the fluctuation | variation is very small, and all corrosion resistance is 3 cc or less. In addition, even in one ceramic honeycomb structure, a uniform reinforcement partition wall portion is formed with a maximum intersection of porosity of 1% or less, so that local corrosion phenomenon hardly occurs in the reinforcement partition wall, and the reinforcement partition improves corrosion resistance as a whole. It was suggested.

Furthermore, the manufacturing method of Examples 2-4, 8-10 which attach a partition wall reinforcement which mixed methylhydrogen silicone oil and dimethyl silicone oil to a partition wall, and the partition wall reinforcement which mixed silicate alkoxy oligomer and dimethyl silicone oil In the manufacturing method of Examples 5 to 7 adhering to the partition wall and the manufacturing method of Example 11, in which the partition wall reinforcing agent mixed with methylhydrogen silicone oil and kerosene is attached to the partition wall, methylhydrogen silicone oil or silicate alkoxy oligomer It was recognized that the tendency of decreasing the average porosity of the whole reinforcement partition wall part also by increasing the content rate of is.

Specifically, in the ceramic honeycomb structure obtained in Examples 3, 4, 6, 7, 9 to 11, wherein methylhydrogensilicone oil or silicatealkoxy oligomer is 25% or more, a reinforced partition wall having an average porosity of 21% or less can be obtained. In addition, the effect which has a uniform porosity was added, and corrosion resistance was very large. On the other hand, in the ceramic honeycomb structures obtained in Examples 4, 7 and 10 with 50% methylhydrogensilicone oil or silicatealkoxy oligomer, the reinforcement having an average porosity of 14-15%, 16-17% and 14-15%, respectively. The partition wall part can be obtained, which is more corrosion resistant. Moreover, also in any Example and the comparative example, the obtained ceramic honeycomb structure was recognized the heat shock resistance sufficient in actual use in heat shock temperature 70 degreeC or more. The partition wall reinforcing agent used and the evaluation results are shown in Table 1.

Table 1

As described above, according to the present invention, it is possible to obtain a honeycomb structure having a desired performance without significantly deforming the partition wall while greatly improving the productivity and the cost reduction of the product. In addition, a dense and uniform reinforcement partition wall portion can be formed with high precision, and a ceramic honeycomb structure excellent in corrosion resistance can be stably obtained. Of course, the obtained ceramic honeycomb structure has a very uniform porosity with respect to the entire reinforcement partition wall portion, and has better corrosion resistance because local corrosion phenomenon can be almost completely avoided.

Claims (20)

A cell composite including a plurality of cells serving as a flow path of a fluid partitioned by a plurality of partition walls having a porous structure, and an outer wall having a porous structure surrounding and holding the outermost circumferential cell positioned at the outermost circumference of the cell composite. As a ceramic honeycomb structure, The portion of the cell wall located at at least one cell opening end of the cell composite has a higher strength than the portion other than the at least one cell opening end (normal partition wall part), and the variation in porosity per unit volume is within ± 2%. A ceramic honeycomb structure, comprising a phosphor reinforced partition wall. The ceramic honeycomb structure according to claim 1, wherein a value of the porosity (%) of the reinforcing partition wall portion is at least 3% smaller than a value of the porosity (%) of the regular partition wall portion. The ceramic honeycomb structure according to claim 1 or 2, wherein a porosity of the reinforcing partition wall portion is 30% or less. The ceramic honeycomb structure according to any one of claims 1 to 3, wherein the minimum partition wall thickness of the partition wall is 0.030 to 0.076 mm. The ceramic honeycomb structure according to any one of claims 1 to 4, wherein the length from the end face to the tip of the cell opening end of the reinforcement partition wall portion is not the same as the entire reinforcement partition wall portion. The ceramic honeycomb structure according to any one of claims 1 to 5, wherein the partition wall thickness of the reinforcing partition wall portion is thicker than the partition wall thickness of the regular partition wall portion. The cell according to any one of claims 1 to 6, wherein any one cell within a third to twenty-second range in which the outermost circumferential cell is located inside the starting cell and the starting cell is located inside the end cell and the end cell. If the cell located at is the default cell, The thicknesses Tr ₁ and Tr _{3 to 20} of the partition walls constituting each of the starting and end cells and the thickness Tc of the partition walls constituting the basic cell are 1.10 ≦ (Tr ₁ , Tr _{3 to 20).} Ceramic honeycomb structure, which satisfies the relationship of) /Tc≦3.00. The ceramic according to any one of claims 1 to 7, which is composed of at least one ceramic selected from the group consisting of cordierite, alumina, mullite, silicon nitride, aluminum titanate, zirconia, and silicon carbide. Honeycomb structure. The ceramic honeycomb structure according to any one of claims 1 to 8, wherein the cross-sectional shape perpendicular to the flow path is a shape of a circle, an ellipse, a manor, a trapezoid, a triangle, a square, a hexagon, or a bilateral asymmetry. 10. The ceramic honeycomb structure according to any one of the preceding claims, wherein the cross-sectional shape perpendicular to the flow path of the cell is triangular, square or hexagonal. The ceramic honeycomb structure according to any one of claims 1 to 10, which is used for a carrier for purification catalysts for automobile exhaust gas. The ceramic honeycomb structure according to any one of claims 1 to 11, wherein a catalyst component is supported on the partition wall and held on an outer circumferential surface of the outer wall to be embedded in a catalytic converter. Using a clay material composed mainly of ceramic material, a substrate having a honeycomb structure having a plurality of partition walls is obtained, and a partition wall reinforcing agent is applied to a portion of the partition wall located at at least one cell opening end of the substrate. As a method for producing a ceramic honeycomb structure that is baked after being adhered, A method for producing a ceramic honeycomb structural body, comprising as a partition wall reinforcing agent a compound having as a main component a compound having at least one element selected from the group consisting of Si, Ti, Mg, and Al in its structure. The method for producing a ceramic honeycomb structure according to claim 13, wherein the main component of the partition wall reinforcing agent is a compound which is burned to produce an inorganic oxide. The method for producing a ceramic honeycomb structure according to claim 13 or 14, wherein the main component of the partition wall reinforcing agent is a compound having a siloxane bond. The method for producing a ceramic honeycomb structure according to any one of claims 13 to 15, wherein the main component of the partition wall reinforcing agent is silicone oil, silicone varnish, alkoxy oligomer or a mixture thereof. The method for producing a ceramic honeycomb structural body according to any one of claims 13 to 16, wherein an absolute viscosity of the partition wall reinforcing agent is 1 to 10000 mPa · s. The method for producing a ceramic honeycomb structure according to any one of claims 13 to 17, wherein the ceramic material is a cordierite raw material. The method for producing a ceramic honeycomb structure according to any one of claims 13 to 18, wherein the clay contains a water-soluble organic binder. The method of claim 19, wherein the water-soluble organic binder is composed of at least one water-soluble compound selected from the group consisting of hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol and polyvinyl acetal. Method for producing a ceramic honeycomb structure.